The background of multicarrier modulation/demodulation of data will first be explained wish reference to the attached FIG. 1 to 4. A general review article, which describes such basic aspects and which relates to the preamble of the attached claims 1, 14, 23, is published in IEEE Communications Magazine, May 1990, pages 6 to 14, "Multicarrier Modulation for Data Transmission: An Idea Whose Time Has Come" by John A. C. Bingham.